1. Field of the Invention
The present invention relates, in general, to external skeletal fixation systems and, more specifically, to an external skeletal fixation system including improved means for connecting a first external fixation bar to a second external fixation bar, etc., in a manner which prevents at least one of the external fixation bars from rotating about its longitudinal axes.
2. Description of the Related Art
Fractures of bone structure can be treated surgically, inter alia, by external fixation, by internal fixation, or by osteosynthesis. External fixation is commonly utilized to treat acute fractures of the skeleton, soft tissue injuries, delayed union of the skeleton when bones are slow to heal, nonunion of the skeleton when bones have not healed, malunion whereby broken or fractured bones have healed in a malposition, congenital deformities whereby bones develop a malposition, and bone lengthening, widening, or twisting.
External fixation systems typically include an elongated external frame, a plurality of threaded and/or smooth pins and/or threaded and/or smooth and/or beaded wires, etc., for attaching to bone structure; and a plurality of external fixation connectors for attaching the pins or wires, etc., to the external fixation frame at desired locations along the length of the frame. The pins or wires may extend completely through the boney skeleton extending out each side of the limb (commonly referred to as "transfixation pins") or may extend through the boney skeleton and out only one side of the limb (commonly referred to as "half pins").
External fixation frames vary considerably in design and capabilities, and may include multiple or single elongated bars or rods for extending generally longitudinally of the boney skeleton; rings or plates for encircling a portion of the boney skeleton, etc. Materials for frames also vary, including metals, alloys, plastics, composites, and ceramics. External fixation frames vary in their ability to accommodate different spatial relations between the pin and bar.
Murray, U.S. Pat. No. 4,483,334, issued Nov. 20, 1984, discloses an external fixation frame including a plurality of bone pins secured to a fractured bone and attached to a plurality of bars by a plurality of connectors. The bars are circular in cross sectional shape and each connector has a slot extending to a circular aperture for receiving one of the bars. A screw extends through each slot in such a manner that tightening the screw will squeeze the circular aperture about the circular bar to secure the bar to the connector.
de Zbikowski, U.S. Pat. No. 4,541,422, issued Sep. 17, 1985, discloses an external fixation frame including a plurality of transfixation pins extending through a fractured bone and attached to a telescopic bar by articulated joints. At least the portion of the bar that is connected to an articulated joint is circular in cross section and each articulated joint has a slot extending to a circular aperture for receiving a bar. A screw extends through the slot in such a manner that tightening the screw will squeeze the circular aperture about the circular portion of the bar to secure the bar to the articulated joint.
Mears, U.S. Pat. No. 4,620,533, issued Nov. 4, 1986, discloses an external fixation frame including a plurality of fixation pins inserted through a fractured bone and attached to a rigid bar through adjustable clamps. Each clamp includes an articulating ball having an axial hole through which a pin extends and having radial slots to allow for compression and consequent locking of the pin when screws are tightened. Mears also discloses a bar-to-bar clamp for coupling one rigid bar to a second rigid bar. Each bar is circular in cross section and the bar-to-bar clamp has a slot which extends to a first circular hole for receiving the first bar and a slot which extends to a second circular hole for receiving the second bar. A screw extends through both slots so that when the screw is tightened, the circular holes will be squeezed about the circular bars to secure the bars to the clamp.
Shearer et al., British Patent 2 077 847 A, issued Jun. 12, 1980, discloses an external fixation frame including a plurality of fixation pins inserted through a fractured bone and attached to a pair of rigid bars through connectors. The bars are connected together by a block having a pair of bores. Each bore is adapted to receive the spherical head of one of the bars. A screw-type vice or clamp mechanism is associated with each bore to squeeze opposing sleeve or jaw members against opposite surfaces of one of the spherical heads to secure the bars to the block.
Nothing in the known prior art discloses or suggests the present invention. More specifically, nothing in the known prior art discloses or suggests an improved connector for an external skeletal fixation system of the type including a first elongated bar having a longitudinal axis and a non-circular cross section and including a second elongated bar having a longitudinal axis; the connector including a body having a first aperture therethrough for receiving the first elongated bar and having a second aperture therethrough for receiving the second elongated bar; the first aperture having a cross section that is at least partly congruent with the cross section of the first elongated bar for receiving the first elongated bar and for preventing rotation of the first elongated bar about the longitudinal axis of the first elongated bar.